A more basic question is: what is HDSM2? Something we debated in the past.
We own 2 Avigilon cameras that use HDSM2 so that's in queue for us to test it.
...what is HDSM2?
Easy. It's NOT transcoding. ;)
I've waded thru the white papers, mulled over the media, delved into the discussions, and perused the patent. And still I can't be certain.
The basic seems idea to be don't stream anymore to the client than it needs/wants or can use.
So using sub streams when possible is part of it. Also digitally cropping streams before transmission when the client has zoomed in on the FOV is another.
The patent mentions recompression as well as frame-rate reduction.
Whether some of these are literally "transcoding" or not is a irrelevant point to me.
IMHO, the important point is whether the stream has to be decoded/recoded in order to accomplish this, and I can't imagine how it wouldn't have to, at least in the case of recompression or digital cropping.
Looking forward to this test as there are a lot of people that don't understand how HDSM V1 works let alone how HDSM V2 works, especially on this site. For those of us that do this should be an interesting test.
UD1, you are welcome to ask John for my e-mail
I will try my best to explain
then you can pass your knowledge to IPVM Team :)
Its true. I've never been able to find a white paper AT ALL that explains HDSM but what I do know and by their own estimation tool, the bandwidth, CPU and storage requirements are heavy and hence the real cost. If you want to dissect it, think about the solution in playback ... how does all that information ie focal planes, fields of view etc all get into the system "after the fact" ? It doesn't..... it goes in live. Mmmmmm howdaydodat?
Does HDSM2 work with only their cameras, or all h.264 cameras?
"what I do know and by their own estimation tool, the bandwidth, CPU and storage requirements are heavy and hence the real cost"
Sorry but this is not true.
"We will solve this mystery!"
"Looks a lot like transcoding!"
So it doesn't transcode, I agree.
But the without transcoding and without JPEG2000, HDSM 2 cannot do what HDSM 1 could, notably send a reduced resolution stream to a client using a higher resolution source.
Without a progressive CODEC, like SVC or JPEG2000, one must decode the stream to do anything with the resolution. Alternatively the camera can stream multiple resolutions, but this is like most other cameras on the market.
What HDSM 2 DOES do (on the camera) is cut up the picture into multiple images or tiles before sending them to ACC. Then when you are digitally zoomed in on an FOV, it only sends enough tiles to show what is necessary.
Since the tiles are split at the camera, no transcoding is necessary to do this.
Any technical arguments welcome.
So it is only if you are digitally zoomed on a high resolution stream between the VMS server and VMS client that there is really an advantage over other methods. No advantage between the VMS server and camera as that would need to record the highest resolution stream at all times anyway.
Looks to me that there is little advantage over transcoding unless you are zoomed in on a large number of streams simultaneously, since transcoding a single stream doesn't have that much overhead (say compared to transcoding every stream on a VMS).
Am I correct?
Gentleman's, why don't all of you log into Avigilon demo
and play as much as u want with HDSM2
Avigilon demo site info can be gladly provided by partners,sales, and IPVM :)
Bottom line for me is that the "tiling solution" of HDSM is a unique and practical way of reducing bandwidth usage when digitally zooming.
That said, it's also kludgey and arbitrary. Consider that depending where.you zoom in on the screen, you might require 1x, 2x, 3x or 4x the bandwidth because where the fixed tile boundaries lie.
IMO, HDSM 1 with JPEG2000, was more elegant, due the format's built in progressive scaling.
Avigilon allows a user to change the display quality within the client to 4 different levels. I think HDSM must play a role in that quality selection because the cameras appear to only send a high and low resolution stream. I'm not sure how many company's provide that setting, but its very useful for Avigilon.
Those quality settings in the client help HDSM determine when the client gets a high or low resolution stream from the server. However, HDSM must some how reduce the video decompression needed even further and its happening on the client because the server doesn't mind how much work the clients are doing.
So is HDSM really a streaming technology or just a decompression method?
Will anybody answer main ? of this topic, please
Does Anybody Know Another VMS Which Has The Same/Similar Streaming Technology As Avigilon HDSM2?